In Japanese, there are many "forms" of words you can use. There's short form, masu form, te form, etc. Since my finals are coming up next week, I want to make a card on "tai form".
tai (たい) means to want. It is used to describe your hope or aspiration!
ねたいです！(netai desu!) Neru (ねる) means to sleep. It is also a "ru verb". When you conjugate ru verbs, all you have to do is drop the ru(る) and add whatever form you're using (in this case, we're using tai form). This is how you say "I want to sleep!" ねたいです！ ね(ne) た(ta) い(i, pronounced ee like needle) で(de) す(su). Anime: Kotoura-san (琴浦さん)